This is for rpi003.Graphs.

Hardware:

Type.	Description.	Sponsor	Webshop
CPU	Raspberry Model B Revision 2.0 Mounting holes, Single-core 700Mhz BCM2835 , 512 MB 000d	None	None
GPS	NEO-6M-0-001	None	None
PCB	Dual Side Prototype PCB	None	None
PSU	Cheap USB PSU	None	None
Case	RS online Case	None	None
Antenna	Cheap active outdoor antenna	None	None

Here is the current time sync status +/- 2 msec. total on the graph.

Due to it is GPS sync
Here is the time sync status 5.0k = 0.005 ms on the graph.

I have made a start image of the linux installation i plan to use. - Guide and image is found under Guides > GPS Sync NTP Server.

Here is the work in progress setup.
The GPS antenna is only for testing.. Mount a external antenna, with clear view to satelites, and low reflection from other surfaces.

Log

2017-02-06 Graps was not updating - due to stats whas running on old secondary ip of the box. - Corrected now.
2017-02-06 Short power outage. - ntpd did not start - Tryed to reboot - Running again !
2017-02-02 Still large offset try "service ntp restart" - due to no jitter on SHM(0) and "cgps -s" Graph
2017-02-01 Discovred large offset +- 90 ms starting from 2017-01-31 18:00 anter 174 dayes uptime. Tryed "service gpsd restart" due to high offset on the pps signal
2017-01-01 Due to test of missing leapsetup, ntp service restarted - to fix the 1 sec. Everything worked fine on rpi001
2016-10-12 Looking at my firewall, An old Cisco PIX506e, with uptime 4 years 241 days. Datasheet say Max simultaneous connections 25.000 It looks like I run in the high end of connections
2016-10-12 Uptime is now 63 days, and with “Net speed: 1000 Mbit” set on www.pool.ntp.org - No problems detect yet.
2016-09-23 Uptime is now 44 days, and near 1 month with “Net speed: 1000 Mbit” set on www.pool.ntp.org - No problems detect yet.
2016-09-22 Changed internal ip address - Small interupt (less than 1 sec) due to "clear xlate" on firewall to activate this change external.
2016-08-24 Speed change on www.pool.ntp.org to "Net speed: 1000 Mbit To take more load..- 1 Mbit - 10 Mbit - 100 Mbit graph (CPU UDP Connections)- No problems yet.
2016-08-22 Speed change on www.pool.ntp.org to "Net speed: 100 Mbit"
2016-08-21 Verify that it handles more NTP requests 2016-08-20 Speed change on www.pool.ntp.org to "Net speed: 10 Mbit"
2016-08-17 MRTG Grap was changed to scale +- 2 ms on this page
2016-08-17 Can see that the server is taking network traffic, so it is serving clients rpi003 UDP traffic and rpi003 Networktraffic
2016-08-16 Join tne NTP www.pool.ntp.org with this server "Net speed: 1 Mbit"
2016-08-10 It was installed - using GPS sync.